[xmonad] darcs patch: XDG_CONFIG_HOME support

[Isaac Dupree]

It's a freedesktop.org standard that we should support... it doesn't 
hurt us and it will potentially help that standard become exponentially 
more popular (e.g. even my shell, "fish", uses it, and it appears that 
gtk+ and compiz use it, and several other things I have installed, and 
XFCE uses it...).  Right now I have $HOME as a subdirectory of what is 
morally my home directory in order to keep the config files etc. 
together, like I keep my other stuff together in directories.  Which 
does indeed have the potential to help mounting/networking.

-Isaac